PROJECT SUMMARY The long-term goal of this project is to understand the fundamental mechanisms that regulate human copper (Cu) homeostasis in the central nervous system. Cu is essential for numerous physiologic processes, including myelination of neurons, immune response, catecholamines balance, mitochondria respiration, and protection against oxygen radicals. Disrupted Cu homeostasis causes or significantly contributes to the pathogenesis of several neurodegenerative disorders including Menkes disease, Wilson disease, MEDNIK syndrome, and Alzheimer's disease. The molecular mechanisms that govern Cu homeostasis in most cells of the central nervous system, especially during metabolic changes, are greatly understudied and poorly understood. This project will feel the information gap by characterizing the biochemical mechanisms of Cu transport and utilization in noradrenergic neurons (NEN) of locus coeruleus. The experiments will determine specific roles of the two Cu-transporting ATPases (Cu-ATPase) ATP7A and ATP7B in the maintenance of the cytosolic Cu balance in these neurons and in activation of dopamine-?-hydroxylase (DBH), the key enzyme involved in biosynthesis of norepinephrine. The studies will also characterize the NEN-specific regulatory mechanisms that coordinate the Cu-ATPases activity with DBH secretion. The research program has three specific aims. Experiments under Aim 1 will elucidate how ATP7A, ATP7B and the Cu chaperone Atox1 work together to maintain Cu homeostasis in noradrenergic neurons. Studies under Aim 2 will determine the role of Cu- ATPases ATP7A and ATP7B in activation and secretion of dopamine-?-hydroxylase (DBH), and Aim 3 will characterize the novel feedback pathway by investigating how Cu counteracts the inhibitory effect of NE on DBH secretion. The results will help to develop new mechanistic paradigms of Cu homeostasis in the brain, contribute to understanding of Wilson disease pathogenesis, and, ultimately, help to design better treatments for disorders of Cu misbalance.